What happened to wp admin?

Question

css

I put down all the correct rights, checked htaccess, disabled plugins, did not help.

Answer 1

The first two questions are not clear.
2.1. Body does not need to specify any paddings and margins. For header write padding-top: 15px.
2.2. It is hard to say.
2.3. For footer write padding-top: 15px.
PS In general, it is difficult to answer the question and advise something without seeing the layout. For different cases, the code is written in different ways.

Answer 2

Bootstrap uses floats, there is no clear percentage for a semi-rubber site to make an ideal grid.
Try Flexbox https://html5.by/blog/flexbox/ , left\right alignment with space-between property works perfectly on them (or grids, but they are a bit more complicated)

Answer 3

Possibly hacked. Recently I saw the same thing. Moreover, it was not hacked through WP, but through ModX, which is located on the same hosting account. As a result, I observed the same picture in the WP admin panel.